[hynek]

Being a gatekeeper from unit testing is the last thing I aspire to be, but past me (and that’s my imaginary audience) would’ve loved this explanation before he got some projects into mocking hell.

I’m the first to say that if you have no tests and no idea how to get start, go with end-to-end tests first and take it from there. That doesn’t mean that guidelines that help you to have less brittle and more idiomatic unit tests are bad per se IMHO.

[luigi23]

I have an idea and I know how to get started. Not doing end-to-end because I also do unit tests and they improve my API. It's just that they're not perfect, especially duration-wise. My point is that I don't want get discouraged by being confused about best practices. Most of the software suffers from any testing, and many juniors read articles like these. Seniors do YOLO, correctly or their own way.

Bit offtop, not debunking the content of this post though!

[yojo]

I have personally worked on a team where velocity collapsed under the weight of the test suite.

There were lots of brittle mocks. I think we even did mock out the Ruby equivalent of the HTTP client.

Every change would inevitably break tests (not functionality!) and developers were spending more than half their time wrestling with the test suite.

All of us could have used this article.

Please always strive to improve your practice. Commit things that aren’t perfect, but try to internalize best practices over time. Gradually raise your own code quality bar as you get better.

Learning from posts like the OP is super important if you don’t have a good senior Eng on your team. A group of smart juniors can easily code themselves into a hole of left to their own devices. I know this, because I did this.

[hynek]

FWIW I’m a former senior-less junior that programmed himself into a hole. My blog and conference talks are exactly the material that I’d loved to have had ~10 years ago.

Not sure if I’d have been smart enough to take my advice though. ;)

[pydry]

>Every change would inevitably break tests (not functionality!) and developers were spending more than half their time wrestling with the test suite.

I find that this invariably happens because the team tries to test implementation at a very low level rather than behavior at a high level.

I blame an overemphasis on unit tests over integration testing (e.g. J B Rainsberger's inane rant) and tutorials that imply that, for example, if you build a class you have to have some tests for that class.

[icedchai]

At a previous company, someone established a "rule" that every "new function or method" needed its own test. Unless you lucked out with a lax reviewer (like me!) , your code would not pass review if this wasn't followed. Meanwhile, there were basically zero integration or e2e tests. People spent more time adding and maintaining useless tests...

[the_gipsy]

These sound like checksum tests. If you touch anything, they fail. That's all they do now, alert you that yes, you touched that code, now go figure the new checksum for the next poor soul.

[iratewizard]

Agreed. One thing Juniors don't get (and some seniors) is when to test. I see them writing tests on business logic and have to correct them regularly. I've had to sit down and explain to 3rd party technical resources that they're foolishly asking for more technical debt by asking for certain tests.

The other thing Juniors don't get is prototyping. I regularly build something quickly to get the problem set into my head. If it's good enough, I'll leave it. If it's got issues, I'll throw it away and start fresh now that I know what I'm solving. Juniors don't work fast enough or effective enough to do things like that without putting timelines at risk. Plus, they frequently want to do some cargo cult methodology of the week like TDD.

[nescioquid]

> I see them writing tests on business logic and have to correct them regularly.

Are you saying you have to tell the developers not to test business logic, or that you have to fix the tests they write?

[iratewizard]

The former. Business logic changes regularly. New phases of projects frequently require changes that break the unnecessary business logic test code.

Test code should fail when an important underlying mechanism regresses. If it always fails on the next phase of the project because some hapless idiot needed to cover every line, the signal to noise ratio gets weaker and the purpose of the test code is lost.

[nescioquid]

Thanks for the clarification -- that's what I suspected, but thought I must be misreading or misunderstanding, but I also don't know your situation and trust you're making the right set of trade-offs here. If your system is today a cuttlefish, yesterday a cow, and tomorrow a crab, cow tests don't do you much good. That sounds like a crazy environment, and I'd maybe have a care that those hapless idiots are sane people in an insane place.

[iratewizard]

You sound like you're in that category if you can't differentiate and think that it's surprising for software to have a flexible business logic layer.

[BlargMcLarg]

Counterpoint, I've not seen seniority affect these outcomes at all. Most of the time I see some management type or CTO heavily push the "code coverage / test everything" narrative which then rolls down the hill. Strategy did not seem at all correlated with seniority.

Same goes for prototyping. I don't see much of a correlation between willingness to prototype and seniority, either.

[icedchai]

I worked at a place that had a "increase test coverage" dogma. If you ran out of real work, which was common due to poor management, you'd wind up with an awful "increase test coverage to 80%" ticket to keep you busy. This resulted in at least one guy quitting because he said it was a useless waste of time.

[hynek]

I can assure you that it is possible and meaningful to have full code coverage in certain contexts (for instance for important projects that get only rarely touched) and doesn’t inevitably lead to bad test suites.

Railing against code coverage is at this point just as dogma as insisting on it.

[BlargMcLarg]

Not sure why you're highlighting this in a sub-thread regarding the importance of context. Surely this was already implied?

What I'm railing against is the idea that seniority is a prime indicator to the effective strategy parent comment insists on, which simply doesn't mirror my experiences. What I see is juniors picking up the habits of their superiors. They're learning this dogmatism from somewhere.

[hynek]

I’m sorry I’ve apparently misunderstood your point. I guess I’ve never seen too brass imparting more than a big picture “we’re writing tests now”.

[iratewizard]

> Same goes for prototyping. I don't see much of a correlation between willingness to prototype and seniority, either.

Willingness is one thing, but getting yelled at for learning and doing your best is another. I never treat my Juniors like that, and encourage a 75/25 working/improving split. Still, several frequently get anxiety about how long it's taking them to clear tickets.

[hinkley]

> go with end-to-end tests

I've found that E2E tests make for a pretty bad case of hill-climbing where tests are concerned. To the point where I think that's the pathology of the testing icecream cone.

It's easier conceptually go to 'up' the testing tree from unit tests to E2E tests, than it is to come down. People do what they are most familiar with, and if the E2E tests are first, then they are the most familiar. They are also glitchy as hell, and I see disdain for that get applied to all tests, not just the human tragedy that Selenium turned out to be. Also the ways in which unit test habits are considered 'bad' in functional tests are either less consequential or easier to walk away from. I'm not entirely sure which it is, or if it's both, but it's definitely less painful to relearn.

We also overvalue the E2E test versus human testing. I can't count how many times someone has come to tell me a login button is broken, 20 minutes before the E2E tests fail and tell me the same thing. Computers arbitrating code regressions are half the point of CI, so if your tests aren't arbitrating, they aren't doing their job, and should be fired.

[pydry]

E2E have higher capex and lower opex - hard to set up well, cheap to maintain if you do.

Low level tests are the reverse - easy to get started, hard to maintain.

If youve got a really well oiled framework e2e tests are spectacular but getting to that point can vary between easy and "harder than the actual project itself" and if you half ass it (which most people do) it ends up a useless flaky mess.

[hinkley]

> cheap to maintain if you do.

I've only seen this with projects in maintenance mode. Any major functionality changes tend to land teeth-first in the E2E tests, and after a few cycles of that you start dragging your feet a bit on major changes. E2E tests tend to lock in assumptions about the structure of your application, not just the minutia (which is not without its own set of problems).

It is more difficult to get people to write maintainable E2E tests than it is getting them to write maintainable application code, so I've retreated and retrenched.

[pydry]

Weird Ive always found the opposite - E2E tests tend to make the fewest assumptions about the way the application is built.

In most cases we could literally rewrite the whole app in a different language and barely change the tests.

E2E tests do require a solid infrastructure though. If you have tooling problems you cant fix (e.g. you hit selenium's dark corners way too frequently because your web app is even a bit quirky) then maintainence cost can quite quickly exceed any benefit you derive.

Ive also hit this problem of "Id have to create my own equivalent of selenium for interacting with this app's interface" a few times and yeah, the required engineering effort to do it well explodes to the point where its just not worth it.

[BeetleB]

> It's easier conceptually go to 'up' the testing tree from unit tests to E2E tests, than it is to come down.

It all depends on the language and the project, but my experience is usually the opposite. It's often much easier to write an end to end test. To be able to write a unit test you usually have to architect the code to make it easy to mock, etc - and that takes significant skill for most real world projects.

E2E tests have a lot of downsides, but being challenging to write is probably not one of them.

[quickthrower2]

I took it as: if you only have E2E tests then retrofitting unit tests is hard.

My experience agrees with this. Adding unit tests to untestable code (think: class has 10 dependencies that it news up being the first branching of a depdendecy graph to be untangled) requires refactors that just don’t get done with the busyness of other priorities.

[BeetleB]

> I took it as: if you only have E2E tests then retrofitting unit tests is hard.

That's been my experience. My point is that the reason the project has E2E tests and not unit tests is because it was easier to add E2E tests.

[the_gipsy]

Yea, you definitely don't want people writing e2e tests because it's easier than writing other tests or because there aren't any other tests.

[hynek]

I’m aware of all the problems that e2e tests have, and yet I find it more useful to have 1 test that adds something to a basket and 1 test that removes it than 100 unit tests without contract tests (which I never got the hang of TBH).

(To be fair, my projects are low on JavaScript which somewhat changes the trade-off calculations, but I haven’t seen any assertions about project types above.)